BUCKET AS-GENERAL PURPOSE 2239730 - Caterpillar

Closed Circuit Oil Flow - High Amplitude
The vibratory hydraulic circuit is an open loop closed circuit hydrostatic system.The vibratory system starts operating when: * Vibratory mode selector switch is placed in the double drum vibratory mode.* Vibratory switch is on.* Automatic mode is selected.* Control handle is moved 40% to 70% in the forward direction.Control valves (2) and (14) are not energized. The solenoid in control valve (10) is energized, the spool shifts to the envelope shown. Control oil is directed through control valve (10) to servo piston (9). Servo piston (9) moves the swashplate in pump (8). The swashplate angle in pump (8) increases, output oil flows from pump (8) through closed circuit line (7).Oil flows through circuit line (7) to motor (1). Resistance in flow at motor (1) creates the high pressure side of closed circuit line (7) as shown. Oil flows from motor (1) to motor (13) and creates the transmission circuit. The oil leaving motor (13) flows back to pump (8) through circuit line (17) and becomes the low pressure (return) side of the closed circuit as shown.The increase in pressure causes shuttle valve (4) to shift and direct pilot oil from the high pressure side of the closed circuit to POR valve (3). When the pressure increases to the setting of POR valve (3), POR valve (3) opens and dumps control circuit oil to tank. POR orifice (22) limits immediate replenishing of the control circuit, allowing the control circuit pressure to drop momentarily. The drop in pressure limits the rate at which the swashplate in pump (8) can stroke. Circuit pressure will not exceed the POR setting.The swashplate will continue to stroke at a reduced rate until servo piston (9) hits the displacement limiter.POR valve (3) limits the working pressure of the system. As leakage and flushing occurs in the closed circuit, the make-up check valve function of combination valve (20) replenishes the circuit with charge oil. Charge oil replenishes the circuit when the pressure drops below the charge circuit pressure.Oil in the high pressure side of the circuit flows to combination valve (18). The main relief function of combination valve (18) limits any high pressure spikes in the circuit. It does not limit the working pressure of the system. The main relief function of combination valve (18) is set at 36 000 1700 kPa (5220 250 psi).When both control valves (2) and (14) are not energized, oil flow is directed to motors (1) and (13). There is a pressure drop in system pressure across motor (1). Use the formula below to figure the pressure drop across motor (1). Pilot oil in the transmission circuit operates inter circuit and anti cavitation relief valve (15). SEE: For information on inter circuit and anti cavitation relief valve (15), see the Cooling And Control Valve section of this module.Transmission circuit oil flows through motor (13) propelling the vibratory weights in the rear drum. The oil leaving motor (13) is the return oil at charge